How many times are these values updated. My sites jump around on SERP's tremendously, but they are new; however, a lot of other sites are rock solid. I have been doing alot of link building lately and backlinks + PR just updated recently. Do backlinks only update per quarter, or all the time? What im asking is that can the backlinks I most recently built be counted before the next BL update?
Visible backlinks and PR is updated roughly every 3 months however google is constantly updating both on a regular basis
the jumping of your site does not necessarily have something to do with your site. Google is all about patience. Make a change and wait a few weeks especially when your site is new and continue to build backlinks slowly but steadily. They only make backlinks and PR "visible" every now and then but that doesn not mean your values did not change. They are visible to Google.
also remember you could be hitting different google datacenters, so when the serps change they have to roll out to all the data centers which can make it look like they are jumping around more than they are.
Google also seems to be playing with changing the serps based on time of day, day of week, time of year, and region. I'm not sure how far they've gotten into this, but you can see obvious differences in the serps based on where the person doing the search is physically located. I often check my incoming URLs in my stats. Often when I try an exact search that someone did to get to my site, my site will show on a different page of the search results (sometimes better sometimes worse). In the latest Google patent, Google stated that it will be trying to make the serps more dynamic, ie relevant to the search, based on the things I listed above.
You can confirm this fact by subscribing to some Google alerts, you will find that most searches change some almost daily. http://www.google.com/alerts/manage?hl=en You will have to sign into Google to do this.